Agenda for next week’s Summit of Americas in Los Angeles has firmed up. But not its guest list.

With just a week until the Biden administration hosts the ninth Summit of the Americas in Los Angeles, the agenda is set but the guest list remains shrouded in mystery.

President Biden will host the hemispheric meeting, set to begin Monday, with a focus on what senior administration officials say are the core challenges facing the region: curbing record migration, boosting economic growth, combating climate change and bolstering recovery from the COVID-19 pandemic.

Topping the agenda is tackling the historic flows of migration and addressing the nearly 7 million people who have been displaced from their homes in the region, according to a senior administration official who spoke on condition of anonymity to describe summit preparations.

Biden will stand “shoulder to shoulder” with foreign leaders across the region on the last day of the summit as part of a “bold new plan” to stem migration, the official said.

But the White House remains circumspect about who will actually attend the high-stakes regional conference. That includes whether Mexican President Andrés Manuel López Obrador, who leads Latin America’s second-most-populous country, will be among the leaders standing by Biden’s side.

Divisions over the U.S. decision to exclude the authoritarian leaders of Cuba, Nicaragua and Venezuela have thrown the guest list into doubt, with the loudest criticism coming from López Obrador, who has yet to decide whether he will attend.

The leaders of Bolivia, Chile and Honduras have expressed doubt about coming to Los Angeles. Meanwhile, most of the Caribbean countries have backed off a threat to boycott.

Every host nation of the summit has discretion in drawing up the guest list, and most if not all countries are routinely included. This is the first time the summit, which takes place every three or four years, is being held in the U.S. since its 1994 inaugural session in Miami.

The Mexican president said Friday he would wait to see whether the U.S. meets his request to invite all countries in the Western Hemisphere, but signaled that he would send a delegate in his place, most likely his U.S.-friendly foreign secretary, Marcelo Ebrard.

White House officials said conversations with the Mexican president have been “respectful,” and that his absence would not undermine the summit’s ambitious agenda. Officials said participants would announce a set of policy decisions highlighting law enforcement cooperation and tackling the criminal smuggling industry. Leaders will also promote agreements that boost support for refugee resettlement and stabilization efforts, as well as promote labor mobility benefiting the U.S. and Canada, which are experiencing labor shortages.

Biden is expected to begin an initiative to promote health infrastructure and training for health workers in the region to help countries prepare for future pandemics, according to senior administration officials.

Vice President Kamala Harris, who has been tasked with tackling the root causes of migration in the region, will announce a partnership combating climate and energy challenges facing Caribbean nations, officials said. The effort is expected to build on the Caribbean Energy Security Initiative to help those nations overcome their dependence on fossil fuels, an initiative that was started by Biden in 2013 when he was vice president.

Times staff writer Tracy Wilkinson contributed to this report.